Starting this year, Zuckerberg will only qualify for 40 under 40 lists. Yes, he's turning 30 and his age is showing. The young CEO is famed for taking on a big challenge each year. In the past, they have been cool ones: learning Mandarin; only eating animals he killed with his bare, coding hands; and talking to at least one non-Facebook employee every day. (Okay, that last one is kind of sad.) This year, in a mature nod to Emily Post, his big challenge to himself is.... drumroll... to write a thank-you note every day.

Mark Zuckerberg isn't mad at Snapchat CEO Evan "We-don't-want-your-$3-billion" Spiegel for posting his private, courting emails on Twitter. "Oh, I don’t know, that’s probably not what I would have done," said Zuckerberg, going on to say all entrepreneurs make mistakes. Time will only tell if Snapchat's bigger mistake was turning down Facebook's acquisition offer.

Zuckerberg's wife is ready to make little Zucks, but he's not ready yet.

Everyone at Facebook knows that year-old Graph Search sucks. "When it’s suggested that Graph Search works about half the time, Zuckerberg says that’s being generous," write Stone and Frier.

The most surprising thing: Zuck isn't all about "real identity" online anymore. Back in 2010, Zuckerberg told The Facebook Effect author David Kirkpatrick that having "two identities is an example of a lack of integrity." Facebook has long been seen as forcing people to be their real selves online, with the hope of tying everything they do across the Web to their name. The company's now stepping that back. Users will be able to log in anonymously to some of Facebook's new apps, reports Bloomberg. "If you’re always under the pressure of real identity, I think that is somewhat of a burden," Zuckerberg says.

Perhaps like the burden of having things you said 5 years earlier thrown back at you after you've changed your mind about something?